Implemented TreeView
Merged
Cleaning
Fix css
Inject splitter
Fix horizontal spliview
Fix styles
add more preferences tests
Control spliter margin in splitview
merge to master; change save frequency to 6 seconds
Merge remote-tracking branch 'upstream/master' into fix-css
Fix nits
Fixed nits
Merge with upstream
Use transition end event instead of timer
Merge pull request #187 from dinhviethoa/98-treeview

Implemented TreeView.
Merged with master
Save/restore splitview position (fixed #203)
Add pack index test.
Merge pull request #204 from dinhviethoa/203-prefs-splitview-position

Save/restore splitview position (fixed #203)